Harry Erwin here, responding to Al Bregman <bregman@HEBB.PSYCH.MCGILL.CA>.
I was at the bat session at the ASZ conference last week, and what I heard
indicates to me that bats quite possibly use some of the same mechanisms
that man-made radars use to track objects in clutter. One of these
mechanisms is the use of a narrow (in time) tracking gate to avoid hearing
echoes from clutter and insect jamming. In a neural system this would
basically involve some biological counterpart to Kalman filtering to
establish the timing of when to open the gate and what az and el to be
expecting the target to appear at. There is evidence from studies of
olfaction (Freeman 1979-1995) that primary cells can be brought nearly to
spiking by reafference, held there by opposing excitatory and inhibitory
signals, and then released to respond _immediately_ to the first afferent
stimulus thereafter. That general approach can be applied to a lot of
problems that need the types of top-down processing that Al Bregman speaks
of.
Hopefully, I'll have more to say on this in a year and a half after I've
finished modeling it.
Harry Erwin
Internet: herwin@gmu.edu
Web Page: http://osf1.gmu.edu/~herwin (contains 'indecent' academic material)
PhD student in comp neurosci: "Glitches happen" & "Meaning is emotional"
Lecturer for CS 211 (advanced C++)